QuestionHi Mark,
I ride an 89 Ninja 600R...great bike, but I've had an on-going problem that even the bike shop hasn't been able to fix. Here are the symptoms: when riding at a constant high speed (50+ mph), for more than 10 minutes the bike starts to feel like it's running out of gas...the throttle becomes unresponsive, there's even a bit of sputtering, and then within about 30 seconds it stalls completely. I have to pull over, wait a few minutes and then use the choke to start it up again (even though it's still warmed up). It seems like it's not getting enough gas...and the bike shop has checked the fuel lines, but nothing's being pinched. The bike also tends to run fairly hot when this is happening. Any suggestions? Thanks!
AnswerHi Jasmine,
If the gas tank vent is un-obstructed, there are no pinched fuel or vacuum hoses, and vacuum hoses are not collasping when engine is running, the carburetor vents are un-obstructed, and spark plugs look normal like, then:
I suspect fuel flow may be restricted by a partially obstructed pectcock fuel filter, or by rust in the float bowls.
Fine rust particles from the gas tank will pass through most fuel filters and collect in the float bowls. These particles suspend with gas in the bowls, but forms a sediment when the gas in bowls is at rest or drained. The rust obstruct the pilot jets and passage ways. The enrichment circuit (choke) share passage ways with the pilot circuit. The engine may start and idle with choke because the choke compensates for the obstructed pilot circuit.
Check gas tank for evidence of rust, even minute amounts. Remove the petcock and examine for contamination. Look for evidence of varnishing of gas in the float bowls.
Keep me advised of your progress.
Respectfully,
Mark Shively
